1. Field of the Invention
The invention concerns a press roll and more particularly, a press roll and press system having a press roll for the treatment of a fibrous material web such as a paper or cardboard web, in at least one press nip.
2. Discussion of Background Information
Press rolls are known in the related art. One such press roll is mentioned in German Patent Application No. DE-U-92 03 395. This press roll is a shoe press roll, and the press sleeve is also supported in a known manner by at least one support device against a solid stationary yoke, which serves as a flexural carrier and is thus bent according to the varying load. Sagging of the yoke may, however, have a disadvantageous effect on the shoe and guidance of the sleeve. It is often advantageous for deviations from a starting position of this shoe and sleeve guidance to occur. In the press roll of the related art, the effect of sagging of the yoke perpendicular to the plane of the press is countered in that the press shoe is movable relative to the yoke. -However, adequate positional stability of the shoe and sleeve guidance has heretofore not been possible. This is especially true for situations when, for example, a press roll is used as a central roll between two additional press rolls and, consequently, the supporting forces act in different directions.
German Patent Application No. DE-A-33 17 455 discloses a known press roll whereby the press sleeve surrounds a non-rotatably mounted hollow carrier, which is supported internally against an inner flexural carrier by a support device. However, this press roll lacks an outer support device enabling variable adjustment of the support forces positioned between the outer carrier and the inner carrier.
It is thus desirable to provide a press roll and press system having a press roll that has none of the aforementioned difficulties.
The present invention provides a press roll, system and method for the treatment of a fibrous material web. The press roll of the present invention forms at least one nip with a respective mating surface, and comprises a non-rotatably mounted carrier, a press sleeve surrounding the carrier, and at least one outer support device disposed between the carrier and the press sleeve, the press sleeve being supported against the carrier at a respective press nip. The press roll also has a sagging control system adapted to control the sagging of the carrier. The sagging control system may also compensate for sagging produced by the forces in the region of the press nip. Two outer support devices may be provided, with a space extending therebetween in a circumferential direction of the press roll. Additionally, the press sleeve may also be supported against the carrier, to form at least two press nips with respective mating surfaces.
According to an aspect of the invention the carrier may be a bimetal carrier and the sagging control system may further provide a heating system to heat the carrier. Furthermore. The carrier may be slotted and a brace may also be provided to brace the slotted carrier. Additionally, a mutual radial bracing device to brace the carrier and the inner carrier may also be provided. The mutual radial bracing device may brace the carrier and the inner carrier by hydraulics, pneumatics, mechanics, thermal, and/or electromagnetics. Alternatively, the carrier may be an outer hollow carrier having a non-rotatably mounted inner carrier disposed therein.
The sagging control system may include an inner support device disposed between the hollow carrier and the inner carrier. The inner support device may include a group of inner support device support elements perpendicularly extending relative to a direction of travel of the web. Furthermore, the hollow carrier and the inner carrier may each be mounted on their respective ends at a point equidistant from each other.
In accordance with another aspect of the invention, the press sleeve may be a flexible press sleeve and be designed as a shoe press roll. The outer support device may further comprise at least one press shoe and a plurality of outer support device support elements disposed in a group perpendicularly extending relative to a direction of travel of the web. Additionally, the inner support device may include at least one group of inner support device support elements perpendicularly extending relative to a direction of travel of the web, and the inner carrier support elements and the outer support device support elements may each include at least one cylinder/piston unit.
The press roll may also comprise at least one inner support device disposed between the carrier and the inner carrier, with the inner support device being configured to apply a force and act in a predetermined direction, wherein the sagging control system controls sagging of the carrier and wherein sagging resulting from different directional pressing forces is compensated. Also, at least two nips may be included. The two outer support devices may also be disposed between the carrier and the press sleeve.
According to yet another aspect of the invention, the direction of action of the inner support device lies in a resultant direction of action of the two outer support devices. Furthermore, each force applied by the two outer support devices may have the same magnitude. Additionally, each of the two outer support devices may be configured to act in a radial direction offset by approximately 120xc2x0. The forces applied by the two outer support devices and the force applied by the inner support device may be at least substantially of the same magnitude and form an equilateral triangle of forces.
The group of outer support device support elements and the inner support device may further have the same pitch and may each have pistons having the same piston area. The forces applied by the two outer support devices may be the same magnitude and form an isosceles triangle of forces with the force applied by the inner support device. Furthermore, the total piston area of the inner support device may generate a force at least substantially compensating the force resulting from the two outer support devices. The group of support elements of the two outer support devices may have the same pitch and the support element pistons may have the same piston area. Also, the total piston area of the inner support device may generate a force at least substantially compensating the force resulting from the two outer support devices. The individual piston areas of the inner support device support elements may be the same size as the individual piston areas of the support elements of the two outer support devices. The total piston area of the inner support device may be determined by the number of the inner support device support elements.
The piston pitch spacing of the inner support devices may be the same as that of the two outer support devices wherein the total piston area of the inner support device may be determined by the size of the individual piston areas. Also, the direction of action of the inner support device may lie in the bisector of the angle between the radial directions of action of the two outer support devices. Furthermore, the forces applied by the two outer support devices may have different magnitudes and may form a scalene triangle of forces with the forces applied by the inner support device. The group of support elements of the two outer support devices may have an unequal pitch and/or different sized piston areas. Additionally, the entire piston area of the inner support device may generate a force at least substantially compensating for the force resulting from the two outer support devices.
According to still another aspect of the invention, each of the two outer support devices comprises at least one press shoe, each press shoe having an equal width extending in the direction of travel of the web. Additionally, the two outer support devices and the inner support device may each have variably adjustable pressure. Sleeve guide rails disposed intermediate the carrier and the press sleeve may also be included, wherein the forces applied by the two outer support devices and the inner support device may be maintained in equilibrium by individual pressures acting on the outer support device support elements and the sleeve guide. Furthermore, the press sleeve may be guided offset relative to the carrier.
Another aspect of the invention provides a press roll that comprises a press sleeve, and a hollow outer carrier having opposed ends secured against torsion; the carrier is disposed within the press sleeve and is adapted to guide the press sleeve. Also provided is a support device adapted to internally support the press sleeve at the at least one press nip, and an inner carrier disposed within the outer carrier. The press sleeve is supported against the inner carrier directly through the hollow carrier sleeve by the support device.
The press sleeve may additionally be flexible. The support device may comprise a support element and a press shoe for guidance on the hollow carrier, with the press shoe being supported directly against the inner carrier by the support element, which may be coupled to the press shoe by a joint. The support device additionally may exert a variably adjustable supporting force. Furthermore, the hollow carrier and the inner carrier may be mounted on their respective ends and at a location equidistant from each other.
Additionally, two support devices and two press nips may be provided, the two press nips defining a space therebetween in the circumferential direction. Each of the two support devices may exert a variable and separately adjustable supporting force. The press sleeve may be in the form of a polygon at at least a section of the press sleeve, at least between the two elongated press nips. Further, the press sleeve may be blind drilled and/or grooved.
The system of the present invention provides a shoe press roll, a first mating roll and a second mating roll, wherein the shoe press roll mates with the first mating roll to form a first press nip therebetween, and the shoe press roll mates with the second mating roll to form a second press nip therebetween, the first press nip and the second press nip elongated in a direction of travel of the web. The web path may be completely closed. Furthermore, the system may further comprise a felt adapted for guidance between the first and second press nips. Also, a pickup felt for guidance through the first and/or press nip may also be provided.
Another aspect of the system provides a deflecting roll, wherein the web is guided therearound. The deflecting roll may also be a suction roll. Also, a drying section may be provided. At least one of the press nips may be double felted. The press sleeve, the first mating roll and the second mating roll may be blind drilled and/or grooved. At least one press nip may be adapted for drainage at least partially by centrifugation into at least one channel.
The system may further comprise an offset roll, where the second mating roll forms a third press nip therewith. The offset roll may be a shoe press roll, and the third press nip may be elongated in the direction of travel of the web. The second mating roll may be heated to facilitate the drainage of the web in the second press nip and the third press nip, and to further facilitate the release of the web from the second mating roll. A heating system may also be provided to heat the deflecting roll, thereby increasing drainage performance of the second press nip.
According to still another aspect of the system, a press roll is disclosed wherein the press sleeve is supported against the inner carrier directly through the hollow carrier sleeve by the support device, a first mating roll, and a second mating roll. The shoe press roll mates with the first mating roll to form a first press nip therebetween, and the shoe press roll mates with the second mating roll to form a second press nip therebetween, the first press nip and the second press nip are elongated in a direction of travel of the web.
The method of treating a fibrous material web comprises providing a shoe press, mating a shoe press roll to a first mating roll to form a first press nip therebetween, mating the shoe press roll to a second mating roll to form a second press nip therebetween, and guiding the web along a felt through the first and second nips. Additionally the method may further comprise guiding the web along the felt around a deflecting roll. The method may yet still comprise guiding the web along the felt through a completely closed web path.
Further, the method may further comprise draining at least one press nip, through centrifugation, into at least one channel, and may also comprise guiding the web along the felt through a third press nip formed by the second mating roll and the press roll. The second mating roll may be heated and the web may be released from the second mating roll. Furthermore, the deflecting roll may be heated and the web may be drained at the second press nip.
Another method of treating a fibrous material web comprises providing a press roll, mating the shoe press roll to a first mating roll to form a first press nip therebetween, mating the shoe press roll to a second mating roll to form a second press nip therebetween, and guiding the web along a felt through the first and second nips.